# Relationship between incident ray and reflected definition

### Incident Ray: Definition & Overview - Video & Lesson Transcript | danunah.info A light ray is incident on a smooth surface and is falling obliquely, making an. Figure 1. The law of reflection states that the angle of reflection equals the angle of. The ray of light that leaves the mirror is known as the reflected ray (labeled R in the diagram). At the point of incidence where the ray strikes the mirror, a line can . Consider a light-ray incident on a plane mirror, as shown in Fig. The law of reflection states that the incident ray, the reflected ray, and the normal to the.

In the diagram, the ray of light approaching the mirror is known as the incident ray labeled I in the diagram.

## All Things Equal

The ray of light that leaves the mirror is known as the reflected ray labeled R in the diagram. At the point of incidence where the ray strikes the mirror, a line can be drawn perpendicular to the surface of the mirror. This line is known as a normal line labeled N in the diagram. The normal line divides the angle between the incident ray and the reflected ray into two equal angles.

### Reflection and Refraction

The angle between the incident ray and the normal is known as the angle of incidence. The angle between the reflected ray and the normal is known as the angle of reflection. These two angles are labeled with the Greek letter "theta" accompanied by a subscript; read as "theta-i" for angle of incidence and "theta-r" for angle of reflection.

What is the angle of incidence?

The law of reflection states that when a ray of light reflects off a surface, the angle of incidence is equal to the angle of reflection. Reflection and the Locating of Images It is common to observe this law at work in a Physics lab such as the one described in the previous part of Lesson 1.

To view an image of a pencil in a mirror, you must sight along a line at the image location. As you sight at the image, light travels to your eye along the path shown in the diagram below.

The diagram shows that the light reflects off the mirror in such a manner that the angle of incidence is equal to the angle of reflection. It just so happens that the light that travels along the line of sight to your eye follows the law of reflection. The reason for this will be discussed later in Lesson 2. If you were to sight along a line at a different location than the image location, it would be impossible for a ray of light to come from the object, reflect off the mirror according to the law of reflection, and subsequently travel to your eye.

Only when you sight at the image, does light from the object reflect off the mirror in accordance with the law of reflection and travel to your eye. This truth is depicted in the diagram below. For example, in Diagram A above, the eye is sighting along a line at a position above the actual image location. For light from the object to reflect off the mirror and travel to the eye, the light would have to reflect in such a way that the angle of incidence is less than the angle of reflection.

In Diagram B above, the eye is sighting along a line at a position below the actual image location. In this case, for light from the object to reflect off the mirror and travel to the eye, the light would have to reflect in such a way that the angle of incidence is more than the angle of reflection.

Neither of these cases would follow the law of reflection. In fact, in each case, the image is not seen when sighting along the indicated line of sight. The walls in the room that you are in do not emit their own light; they reflect the light from the ceiling "lights" overhead. Polished metal surfaces reflect light much like the silver layer on the back side of glass mirrors. A beam of light incident on the metal surface is reflected. Reflection involves two rays - an incoming or incident ray and an outgoing or reflected ray.

• All Things Reflected
• What Is an Incident Ray?
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In Figure 1 we use a single line to illustrate a light ray reflected from the surface. The law of reflection requires that two rays are at identical angles but on opposite sides of the normal which is an imaginary line dashed in Fig. We show in Fig. The dashed line normal is perpendicular to the surface. All Things Equal All reflected light obeys the relationship that the angle of incidence equals the angle of reflection.

Just as images are reflected from the surface of a mirror, light reflected from a smooth water surface also produced a clear image. We call the reflection from a smooth, mirror-like surface specular as shown in Figure 2a.